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		<H3><A name="HDRAUTGRID" ></A>AutoGrid</H3>
		<A NAME="IDX389"></A>
		<P><STRONG>Category</STRONG>
<P>
<A HREF="refgu008.htm#HDRCATREL">Realization</A>
<P><STRONG>Function</STRONG>
<P>
Maps scattered points onto a grid.
<P><STRONG>Syntax</STRONG>
<PRE>
<STRONG>output</STRONG> = AutoGrid(<STRONG>input, densityfactor, nearest,
                  radius,exponent,missing</STRONG>);
</PRE>
<P><STRONG>Inputs</STRONG>
<BR>
<TABLE BORDER>
<TR>
<TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Name
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Type
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Default
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">Description
</TH></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>input</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">field or vector list
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">none
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">field with positions to regrid
</TD></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP"
WIDTH="20%"><TT><STRONG>densityfactor</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">scalar or vector
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">1.0
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">densityfactor for grid
</TD></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>nearest</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">integer or string
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">1
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">number of nearest neighbors to
use
</TD></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>radius</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">scalar
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">appropriate
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">radius from grid point to
consider
</TD></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>exponent</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">scalar
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">1.0
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">weighting exponent
</TD></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>missing</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">value
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">no default
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">missing value to be inserted if
necessary
</TD></TR></TABLE>
<P><STRONG>Outputs</STRONG>
<BR>
<TABLE BORDER>
<TR>
<TH ALIGN="LEFT" VALIGN="TOP" WIDTH="25%">Name
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="25%">Type
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="50%">Description
</TH></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="25%"><TT><STRONG>output</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="25%">field
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="50%">regridded field
</TD></TR></TABLE>
<P><STRONG>Functional Details</STRONG>
<P>
This module uses a specified set of scattered points
(<TT><STRONG>input</STRONG></TT>) to assign data to every position of a grid.
This module differs from Regrid in that you do not supply a grid; one is
constructed automatically for you.
<TABLE CELLPADDING="3">
<TR VALIGN="TOP"><TD><P><B><TT><STRONG>input</STRONG></TT>
</B></TD><TD><P>should be either (1) a field with a 1-, 2-, or 3-dimensional
"positions" component or (2) a list of 1-, 2-, or
3-dimensional vectors.
In the second case, the vectors are interpreted as positions.
</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>densityfactor</STRONG></TT>
</B></TD><TD><P>specifies how to modify the automatically generated grid.
By default the automatically generated grid will have approximately
as many
points as there are points in <TT><STRONG>input</STRONG></TT>, and each cell
will be square. If <TT><STRONG>densityfactor</STRONG></TT> is a single scalar
value, then there will be <TT><STRONG>densityfactor</STRONG></TT> times as
many cells in each dimension. If <TT><STRONG>densityfactor</STRONG></TT> is a
vector, then you can modify the number of cells in each dimension
differentially.
</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>nearest</STRONG></TT>
</B></TD><TD><P>must be an integer or the string "infinity."
An integer value specifies the number of nearest points (to each grid
point) to be used in computing an average data value for that
grid point.
</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>radius</STRONG></TT>
</B></TD><TD><P>By default, only those points within an automatically computed
radius will be considered when assigning data values to grid positions.
This automatically computed radius is twice the largest dimension of a
cell in the grid.
You can explicitly set the radius to a value measured in the units of
the "positions" component of <TT><STRONG>input</STRONG></TT>. If you
specify <TT><STRONG>radius</STRONG></TT>="infinity", then no cutoff in
distance will be used; all points will contribute to the result at each
grid point.
<P>
AutoGrid attaches a "AutoGrid radius" attribute to
<TT><STRONG>output</STRONG></TT>, with a
value equal to the radius used, or the string "infinity".
</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>exponent</STRONG></TT>
</B></TD><TD><P>The averaging method is a weighted average.
The expression for this average is
1&#47;radius<SUP><TT><STRONG>(exponent)</STRONG></TT></SUP>.
The default value is 1.0, reducing the expression to the reciprocal of
the radius.
</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>missing</STRONG></TT>
</B></TD><TD><P>is used when <TT><STRONG>radius</STRONG></TT> is set to a value
other than "infinity." The parameter specifies how to treat those
grid points for which no points in <TT><STRONG>input</STRONG></TT> occur
within the specified radius.
<P>
If <TT><STRONG>missing</STRONG></TT> <I>is not set</I>, the module creates
an "invalid positions" component, and grid points with no
assigned data value are invalidated.
If <TT><STRONG>missing</STRONG></TT> is set, the data value is inserted
for the missing data values.
It must match the data component of <TT><STRONG>input</STRONG></TT> in rank,
type, and shape.
<P>
All components that are position-dependent are treated in the same way
as the "data" component.
</TD></TR></TABLE>
<P><STRONG>Components</STRONG>
<P>
Adds a "connections" component.
The "positions" and "connections" components are those of
<TT><STRONG>grid</STRONG></TT> while all components in
<TT><STRONG>input</STRONG></TT> that depend on
"positions" will be present in the
output, modified by averaging.
<P><STRONG>Example Visual Programs</STRONG>
<PRE>
SIMPLE/AutoGrid.net
ConnectingScatteredPoints
</PRE>
<P><STRONG>See Also</STRONG>
<P>
<A HREF="refgu038.htm#HDRCONNECT">Connect</A>,
<A HREF="refgu115.htm#HDRREGRID">Regrid</A>,
<A HREF="refgu075.htm#HDRINCLUDE">Include</A>
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